Bug 1970578
| Summary: | please create a separate vdso subpackage to accelerate fedora debuginfod service | ||
|---|---|---|---|
| Product: | [Fedora] Fedora | Reporter: | Frank Ch. Eigler <fche> |
| Component: | kernel | Assignee: | Kernel Maintainer List <kernel-maint> |
| Status: | NEW --- | QA Contact: | Fedora Extras Quality Assurance <extras-qa> |
| Severity: | unspecified | Docs Contact: | |
| Priority: | unspecified | ||
| Version: | rawhide | CC: | acaringi, adscvr, airlied, alciregi, amerey, bskeggs, hdegoede, jarodwilson, jeremy, jglisse, jonathan, josef, jwakely, kernel-maint, lgoncalv, linville, masami256, mchehab, mjw, mjw, mliska, ptalbert, steved |
| Target Milestone: | --- | Keywords: | Reopened |
| Target Release: | --- | ||
| Hardware: | Unspecified | ||
| OS: | Unspecified | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | If docs needed, set a value | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2021-06-11 18:44:30 UTC | Type: | Bug |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
Never mind.
I spent some time experimenting with overriding
%global __os_install_post \
# sort debugfiles*list differently \
%__os_install_post
and this hooking process worked.
However, rpm's build/files.c genCpioListAndHeader() sorts rpm manifest lists ANYWAY, so there appears to be nothing a .spec file can do.
(The kernel spec file could still create a separate subrpm for vdso files, and that would completely fix this particular problem.) Our friends at suse have switched to a separate vdso subpackage, to solve precisely this problem. It makes fedora debugging much faster to start up (60s in the worst case down to fractions of a second). Please consider doing the same. Search for separate_vdso here: https://build.opensuse.org/package/view_file/Kernel:stable/kernel-default/kernel-default.spec?expand=1 (In reply to Frank Ch. Eigler from comment #3) > (60s in the worst case down to fractions of a second). Currently about 80s, and due to a server-side misconfiguration it wasn't being cached on the server, so it was quite painful if you're impatient like me. A separate debuginfo package would be nice. Caching helps with this issue but each time a vdso debuginfo is added to the server's cache, there will have to be a client that needs to wait for the decompression to occur. It can be annoying to wait over a minute for this, especially if this occurs during an interactive session (ex. GDB). A separate debuginfo package for the vdso will eliminate all of this extra download time. Yeah, if you are unlucky this takes ~80 seconds just for fetching the vdso debug file. Having a separate user space only debuginfo package would be helpful also in case someone just wants to install the debuginfo and not all the kernel space debuginfo they might not use. |
With Fedora 35 serving debuginfo to gdb etc. via the debuginfod service by default, we see regular queries looking for debuginfo of the userspace-relevant vdso* libraries. This happens even if the user is running gdb on some ordinary program like /bin/ls, because vdso is mapped into userspace, has a buildid, thus gdb tries to fetch its dwarf data. With debuginfod, this request can now be serviced. However, this particular request is a challenge to the server, because it involves decompressing the appropriate kernel-debuginfo file on the fly, and saving the vdso*.so.debug file, then relaying it to to the remote client. The problem is that these files are practically at the END of the -debuginfo compressed-cpio archive, after all the module .ko.debug's (many hundreds), just before the final vmlinux (just the one! :-). That ends up taking something like 60 cpu seconds (!). If it were possible to sort the kernel's main debuginfo*.list file, to put the vdso* files at the front of the file list, these requests could be serviced much earlier, without decompressing the bulk of the file. I believe this code in the rawhide/master branch kernel.spec file is responsible for the sequencing: 1065 %description %{?1:%{1}-}debuginfo\ 1066 This package provides debug information for package %{name}%{?1:-%{1}}.\ 1067 This is required to use SystemTap with %{name}%{?1:-%{1}}-%{KVERREL}.\ 1068 %{expand:%%global _find_debuginfo_opts %{?_find_debuginfo_opts} -p '.*\/usr\/src\/kernels/.*|XXX' -o ignored-debuginfo.lis 1068 t -p '/.*/%%{KVERREL_RE}%{?1:[+]%{1}}/.*|/.*%%{KVERREL_RE}%{?1:\+%{1}}(\.debug)?' -o debuginfo%{?1}.list}\ 1069 %{nil} Would you consider adding a brief postprocessor (two greps?) to sort the vdso* file names earlier? (Another alternative may be to put these into a whole separate subrpm, and other options may exist too.)